Why People Lost Their Fur

Bipedalism didn’t evolve as a way for ancient humans to keep cool during the heat of the day, according to a new model published today (December 12) in Proceedings of the National Academy of Sciences. But once hominins did start walking on two feet, it ignited another change that allowed them to stay cool—the loss of body hair. The new model explains why similarly sized mammals that walk on all fours and that may tend to overheat have not given up their coats.

“If you are already walking upright for other reasons it actually makes the advantage you get from losing hair bigger than if you were on four legs,” said David Wilkinson of John Moores University in Liverpool, who authored the study along with Graeme Ruxton of the University of Glasgow. “You are moving more of your body up above the ground and sweat evaporates more easily” than it can if you were on all fours, because more air will circulate around you, Wilkinson explained.

Wilkinson and Ruxton came to this conclusion after analyzing a mathematical model of body temperatures during activity at different times of the day for quadrupeds and bipeds with and without fur. The model is an update to a previous theory by Peter Wheeler also of John Moores University, who proposed that both hair loss and bipedalism were driven by our need to cool down. His theory was that switching from four to two feet would reduce the amount of an animal’s body in direct sun and thus increase its ability to stay cool.

But Wheeler left out a critical factor, Wilkinson said—animal movement. Stationary animals could just hang out in the shade during the peak of the day to avoid overheating, he noted, while activities such as foraging likely forced early humans into direct sunlight more often.

Taking movement into account, Wilkinson and Ruxton’s model predicted that modern human ancestors would generate much more body heat metabolically as they traveled and hunted than the sun could cause, suggesting that standing upright to avoid the sun, as Wheeler’s model proposed, would have done little to fight overheating.

“In Peter’s models, he had a nice thermal advantage to standing upright,” said Wilkinson, “but now that vanishes in our version of the model.”

The new model further showed that four-legged creatures do not shed body heat as quickly when they lose their fur, suggesting that the loss of body hair would only have been a significant advantage to ancient humans if they were already walking on two feet. Thus, Wilkinson and Ruxton argue that bipedalism arose first—for some reason other than heat loss, such as improved observation of dangers, appearing larger to predators, or freeing the hands for tool use and carrying—then hair loss began, as a way to combat overheating.

The addition of animal movement to the model was key, said Sarah Elton of the Hull York Medical School, UK, who was not involved in the study. “In any environment you move between parts that are shaded and parts that are in open sun…. sometimes you are sheltered from the wind or not.”

But while Elton is generally in praise of the model, she pointed out that, “at the end of the day, it is just a model and models stand and fall on the type of evidence and also on the sensitivity of the model itself,” or the degree to which it is affected by variations in the assumed parameters, such as the climate, early humans’ movements, availability of shade, and so on. “There are other ideas” about why humans may have dropped their body fur, such as selective pressures imposed by the opposite sex, like a preference for hair-free mates.

Markus Rantala of the University of Turku, Finland, who was not convinced by Ruxton and Wilkinson’s model, offered another theory. “My personal opinion is that only selection caused by ectoparasites is able to explain the origin of human nakedness in a satisfactory way,” he said in an email. As humans began to live in fixed home bases and in close quarters, many parasites such as lice and fleas would have flourished. “As the ectoparasite burden on hominids increased, having fewer parasites may have become more important for survival than a warm fur coat,” Rantala said. Less body hair makes ectoparasites easier to spot and pick off.

Rantala also asks why, if the Ruxton-Wilkinson model is correct, did our ancestors not regain hair when they migrated to northern latitudes with cooler climates, about two million years ago. “Our skin color changed but we did not regain the hair,” he said. “There must have been other selective benefits to being naked than just thermoregulatory reasons.”

But by that time, humans may have gained other ways to keep warm, Wilkinson argued. “One possibility is that by the time humans were migrating they probably had fire and possibly clothing.” Although Wilkinson believes in the new model, he’s not surprised that there is some disagreement in the field. “Human evolution is an argumentative area of science,” he said. “ It always has been.”

This is about the accompanying graphic that shows the gradual upright bipedal walk from chimp to modern humans -- it is not correct.Â Ardi (Ardipithecus ramidus) shows that the last common ancestor of humans and chimps (LCA) was not chimp-like but rather more monkey-like.Â Chimps cannot walk upright -- because of the lower spine fusion to the pelvis -- but monkeys can walk upright much like us. The transition from that LCA to fully upright did not occur in stages but rather suddenly.Â It also occurred not in the savanna but in the forest; this means distance walking was not a factor. The Ardi papers in Science were the most important paper of the last decade (or so according to Science).

I do some R&D on human thermoregulation (for commercial products), and comparison with animal models. One of the striking difference with animal models (pigs) is the fine and constant regulation of body temperature by humans, while pigs and rats body temperature varies widely (over 1.5 Celsius between animals and in same animal within 5min of stress or other activities). Another glaring issue is the lack of good animal models - human skin dominated thermoregulatory system is quite unique (pigs and *not* Apes are the most similar to us). Human naked skin thermoregulation is an active system based on controlling the peripheral blood flow (e.g., as visible in white people during physical activity). It is only functional in furless skin areas with particular fat insulation layer (another animal example is rats tails responsible for about 30% of rat thermoregulation). To the above scientific information, I add a layman observation that human cognitive functions become quite impaired by even slight fever (i.e., deviation from normal 37 Celsius). It leads me to think that the special human needs of big brain and reliance on high cognitive skills maintenance lead humans to need better thermoregulation capabilities. Therefore, I suggest the uniquely human naked skin blood flow thermoregulation system is the evolutionary solution to develop such fineÂ thermoregulation capabilities.Â

I had heard that the increased need for temperature regulation to manage a "hotter" brain was a principle reason for loss of body hair.Â Also, the number of hair follicles/cm2 between humans and chimps is nearly identical, but the proportion of primary (fur) follicles to secondary (sweat) follicles is almost exactly reversed.Â As I understand the model in this paper, the ability of a hairless individual to shed heat is greater (and conversely to conserve heat when cool) which makes sense--so bipedalism has nothing to do with hair or the lack thereof.Â This may be consistent with the emergence of bipedalism prior to hairlessness.Â It would be interesting to see how factoring in the differences in sweat production capacity and brain size/complexity/thermal load would influence the model.Â Also, did the change in brain size/complexity/thermal load largely preceed or follow bipedalism? Â

It isn't clear from the analysis described here whether the authors assumed that all mammals dispense the majority of their heat by sweat. Â If the researched did, then there are major categorical problems with their sample sizes and conclusions.

What a funny article.Â Evolution proceeds through natural selection.Â People are relatively hairless now compared to our ancestors for the same likely reason that male peacocks have their fancy tails.Â It doesn't necessarily have to be for any practical purpose other than ability to score a mate.Â

This is about the accompanying graphic that shows the gradual upright bipedal walk from chimp to modern humans -- it is not correct.Â Ardi (Ardipithecus ramidus) shows that the last common ancestor of humans and chimps (LCA) was not chimp-like but rather more monkey-like.Â Chimps cannot walk upright -- because of the lower spine fusion to the pelvis -- but monkeys can walk upright much like us. The transition from that LCA to fully upright did not occur in stages but rather suddenly.Â It also occurred not in the savanna but in the forest; this means distance walking was not a factor. The Ardi papers in Science were the most important paper of the last decade (or so according to Science).

I do some R&D on human thermoregulation (for commercial products), and comparison with animal models. One of the striking difference with animal models (pigs) is the fine and constant regulation of body temperature by humans, while pigs and rats body temperature varies widely (over 1.5 Celsius between animals and in same animal within 5min of stress or other activities). Another glaring issue is the lack of good animal models - human skin dominated thermoregulatory system is quite unique (pigs and *not* Apes are the most similar to us). Human naked skin thermoregulation is an active system based on controlling the peripheral blood flow (e.g., as visible in white people during physical activity). It is only functional in furless skin areas with particular fat insulation layer (another animal example is rats tails responsible for about 30% of rat thermoregulation). To the above scientific information, I add a layman observation that human cognitive functions become quite impaired by even slight fever (i.e., deviation from normal 37 Celsius). It leads me to think that the special human needs of big brain and reliance on high cognitive skills maintenance lead humans to need better thermoregulation capabilities. Therefore, I suggest the uniquely human naked skin blood flow thermoregulation system is the evolutionary solution to develop such fineÂ thermoregulation capabilities.Â

I had heard that the increased need for temperature regulation to manage a "hotter" brain was a principle reason for loss of body hair.Â Also, the number of hair follicles/cm2 between humans and chimps is nearly identical, but the proportion of primary (fur) follicles to secondary (sweat) follicles is almost exactly reversed.Â As I understand the model in this paper, the ability of a hairless individual to shed heat is greater (and conversely to conserve heat when cool) which makes sense--so bipedalism has nothing to do with hair or the lack thereof.Â This may be consistent with the emergence of bipedalism prior to hairlessness.Â It would be interesting to see how factoring in the differences in sweat production capacity and brain size/complexity/thermal load would influence the model.Â Also, did the change in brain size/complexity/thermal load largely preceed or follow bipedalism? Â

It isn't clear from the analysis described here whether the authors assumed that all mammals dispense the majority of their heat by sweat. Â If the researched did, then there are major categorical problems with their sample sizes and conclusions.

What a funny article.Â Evolution proceeds through natural selection.Â People are relatively hairless now compared to our ancestors for the same likely reason that male peacocks have their fancy tails.Â It doesn't necessarily have to be for any practical purpose other than ability to score a mate.Â

This is about the accompanying graphic that shows the gradual upright bipedal walk from chimp to modern humans -- it is not correct.Â Ardi (Ardipithecus ramidus) shows that the last common ancestor of humans and chimps (LCA) was not chimp-like but rather more monkey-like.Â Chimps cannot walk upright -- because of the lower spine fusion to the pelvis -- but monkeys can walk upright much like us. The transition from that LCA to fully upright did not occur in stages but rather suddenly.Â It also occurred not in the savanna but in the forest; this means distance walking was not a factor. The Ardi papers in Science were the most important paper of the last decade (or so according to Science).

I do some R&D on human thermoregulation (for commercial products), and comparison with animal models. One of the striking difference with animal models (pigs) is the fine and constant regulation of body temperature by humans, while pigs and rats body temperature varies widely (over 1.5 Celsius between animals and in same animal within 5min of stress or other activities). Another glaring issue is the lack of good animal models - human skin dominated thermoregulatory system is quite unique (pigs and *not* Apes are the most similar to us). Human naked skin thermoregulation is an active system based on controlling the peripheral blood flow (e.g., as visible in white people during physical activity). It is only functional in furless skin areas with particular fat insulation layer (another animal example is rats tails responsible for about 30% of rat thermoregulation). To the above scientific information, I add a layman observation that human cognitive functions become quite impaired by even slight fever (i.e., deviation from normal 37 Celsius). It leads me to think that the special human needs of big brain and reliance on high cognitive skills maintenance lead humans to need better thermoregulation capabilities. Therefore, I suggest the uniquely human naked skin blood flow thermoregulation system is the evolutionary solution to develop such fineÂ thermoregulation capabilities.Â

I had heard that the increased need for temperature regulation to manage a "hotter" brain was a principle reason for loss of body hair.Â Also, the number of hair follicles/cm2 between humans and chimps is nearly identical, but the proportion of primary (fur) follicles to secondary (sweat) follicles is almost exactly reversed.Â As I understand the model in this paper, the ability of a hairless individual to shed heat is greater (and conversely to conserve heat when cool) which makes sense--so bipedalism has nothing to do with hair or the lack thereof.Â This may be consistent with the emergence of bipedalism prior to hairlessness.Â It would be interesting to see how factoring in the differences in sweat production capacity and brain size/complexity/thermal load would influence the model.Â Also, did the change in brain size/complexity/thermal load largely preceed or follow bipedalism? Â

It isn't clear from the analysis described here whether the authors assumed that all mammals dispense the majority of their heat by sweat. Â If the researched did, then there are major categorical problems with their sample sizes and conclusions.

What a funny article.Â Evolution proceeds through natural selection.Â People are relatively hairless now compared to our ancestors for the same likely reason that male peacocks have their fancy tails.Â It doesn't necessarily have to be for any practical purpose other than ability to score a mate.Â

This study seems to ignore the radically different structure of fur in animals with hide versus the subdermal, dermal and epidermal human anatomy and physiology.Â You can have plenty of hair and still have no fur (e.g.Â human head). The human fascia is much thinner than animal fascia and fat layers beneath animal fur covered hides are thicker. Temperature control mechanisms in animals with fur involving panting make a side by side thermoregulatory comparisonÂ prone to erroneous conclusions.

Also mathematical models of thermoregulation need to be backed up by actual IR filming during various exercise modes so that there is hard science to back up the model. Was this done? If not, the mathematical model could be about as accurate as the NIST's mathematical models on the WTC collapse. Mathematical models can be like trained seals if they are set up improperly (i.e. they confirm your faulty hypothesis).

Wouldn't this reasoning predict naked Giraffes?They stand very high, live in hot climates and must forage and move, being so large. Â On the other hand, the same arguments apply to elephants which ARE naked. Â Why are elephants and people naked, but not Giraffes?

This is all rampant speculation -- and if I were to speculate, I'd go a different direction.Â The Okavango Delta is known for its bipedal baboons and Lechwe antelopes with specialized foot adaptations.Â It has huge transitions between being largely submerged and arid each year.Â I've seen nature videos where animals can be trapped in mud pits as the land dries, utterly unable to escape or defend themselves.Â From a few thousand miles away, it looks like a person could enter such a pit, do as he wished with the trapped animal, and escape alive.Â I'm not sure how well that would work with thick fur though - and so I'm guessing we lost it to help us maneuver.Â Of course, this is the hoary old "aquatic ape hypothesis", except the water is not very deep and often mucky.

This study seems to ignore the radically different structure of fur in animals with hide versus the subdermal, dermal and epidermal human anatomy and physiology.Â You can have plenty of hair and still have no fur (e.g.Â human head). The human fascia is much thinner than animal fascia and fat layers beneath animal fur covered hides are thicker. Temperature control mechanisms in animals with fur involving panting make a side by side thermoregulatory comparisonÂ prone to erroneous conclusions.

Also mathematical models of thermoregulation need to be backed up by actual IR filming during various exercise modes so that there is hard science to back up the model. Was this done? If not, the mathematical model could be about as accurate as the NIST's mathematical models on the WTC collapse. Mathematical models can be like trained seals if they are set up improperly (i.e. they confirm your faulty hypothesis).

Wouldn't this reasoning predict naked Giraffes?They stand very high, live in hot climates and must forage and move, being so large. Â On the other hand, the same arguments apply to elephants which ARE naked. Â Why are elephants and people naked, but not Giraffes?

This is all rampant speculation -- and if I were to speculate, I'd go a different direction.Â The Okavango Delta is known for its bipedal baboons and Lechwe antelopes with specialized foot adaptations.Â It has huge transitions between being largely submerged and arid each year.Â I've seen nature videos where animals can be trapped in mud pits as the land dries, utterly unable to escape or defend themselves.Â From a few thousand miles away, it looks like a person could enter such a pit, do as he wished with the trapped animal, and escape alive.Â I'm not sure how well that would work with thick fur though - and so I'm guessing we lost it to help us maneuver.Â Of course, this is the hoary old "aquatic ape hypothesis", except the water is not very deep and often mucky.

This study seems to ignore the radically different structure of fur in animals with hide versus the subdermal, dermal and epidermal human anatomy and physiology.Â You can have plenty of hair and still have no fur (e.g.Â human head). The human fascia is much thinner than animal fascia and fat layers beneath animal fur covered hides are thicker. Temperature control mechanisms in animals with fur involving panting make a side by side thermoregulatory comparisonÂ prone to erroneous conclusions.

Also mathematical models of thermoregulation need to be backed up by actual IR filming during various exercise modes so that there is hard science to back up the model. Was this done? If not, the mathematical model could be about as accurate as the NIST's mathematical models on the WTC collapse. Mathematical models can be like trained seals if they are set up improperly (i.e. they confirm your faulty hypothesis).

Wouldn't this reasoning predict naked Giraffes?They stand very high, live in hot climates and must forage and move, being so large. Â On the other hand, the same arguments apply to elephants which ARE naked. Â Why are elephants and people naked, but not Giraffes?

This is all rampant speculation -- and if I were to speculate, I'd go a different direction.Â The Okavango Delta is known for its bipedal baboons and Lechwe antelopes with specialized foot adaptations.Â It has huge transitions between being largely submerged and arid each year.Â I've seen nature videos where animals can be trapped in mud pits as the land dries, utterly unable to escape or defend themselves.Â From a few thousand miles away, it looks like a person could enter such a pit, do as he wished with the trapped animal, and escape alive.Â I'm not sure how well that would work with thick fur though - and so I'm guessing we lost it to help us maneuver.Â Of course, this is the hoary old "aquatic ape hypothesis", except the water is not very deep and often mucky.

This again is not a complete picture of the possible adaptation route to our bipedalism and fur less skin. Take into account our subcutaneous fat as isolation against cold circumstances (water) and more sebum (skin fat) that makes MORE perspiration necessary.Â And then: the pigmentation of Homo spec. is very dark. Heating up in the sun happens fast. Fit all this together please and rethink it.

Bipedal pre humans where not open space walkers. The "savannah" option is no longer accepted. The fastest spreading of "us" H. sapiens was along coasts, rivers and even the seas. Most of us are always near water.

This again is not a complete picture of the possible adaptation route to our bipedalism and fur less skin. Take into account our subcutaneous fat as isolation against cold circumstances (water) and more sebum (skin fat) that makes MORE perspiration necessary.Â And then: the pigmentation of Homo spec. is very dark. Heating up in the sun happens fast. Fit all this together please and rethink it.

Bipedal pre humans where not open space walkers. The "savannah" option is no longer accepted. The fastest spreading of "us" H. sapiens was along coasts, rivers and even the seas. Most of us are always near water.

This again is not a complete picture of the possible adaptation route to our bipedalism and fur less skin. Take into account our subcutaneous fat as isolation against cold circumstances (water) and more sebum (skin fat) that makes MORE perspiration necessary.Â And then: the pigmentation of Homo spec. is very dark. Heating up in the sun happens fast. Fit all this together please and rethink it.

Bipedal pre humans where not open space walkers. The "savannah" option is no longer accepted. The fastest spreading of "us" H. sapiens was along coasts, rivers and even the seas. Most of us are always near water.

I do get fed up with the way scientists studiously avoid ever even discussing the Aquatic Ape hypothesis. Â It's considered professional suicide it seems to even mention it, yet there are many suggestive features of human anatomy that support the idea. Â The main reason it's avoided is that its chief proponent has been Elaine Morgan, who was not trained as a scientist. Â Her books on the subject have been increasingly persuasive over the years and I think the hypothesis (and she calls it that - not even gracing it with the word "theory") at least deserves a glance. Â David Attenburgh made two very supportive radio programmes about it a few years ago. Â Frankly, I think it's plain silly of scientists to "look the other way" every time it comes up. Â

I do get fed up with the way scientists studiously avoid ever even discussing the Aquatic Ape hypothesis. Â It's considered professional suicide it seems to even mention it, yet there are many suggestive features of human anatomy that support the idea. Â The main reason it's avoided is that its chief proponent has been Elaine Morgan, who was not trained as a scientist. Â Her books on the subject have been increasingly persuasive over the years and I think the hypothesis (and she calls it that - not even gracing it with the word "theory") at least deserves a glance. Â David Attenburgh made two very supportive radio programmes about it a few years ago. Â Frankly, I think it's plain silly of scientists to "look the other way" every time it comes up. Â

I do get fed up with the way scientists studiously avoid ever even discussing the Aquatic Ape hypothesis. Â It's considered professional suicide it seems to even mention it, yet there are many suggestive features of human anatomy that support the idea. Â The main reason it's avoided is that its chief proponent has been Elaine Morgan, who was not trained as a scientist. Â Her books on the subject have been increasingly persuasive over the years and I think the hypothesis (and she calls it that - not even gracing it with the word "theory") at least deserves a glance. Â David Attenburgh made two very supportive radio programmes about it a few years ago. Â Frankly, I think it's plain silly of scientists to "look the other way" every time it comes up. Â

Once again, an article based on theory rather than fact. Evolution negates God's creations. Why do Apes still have fur if we evolved and lost the fur? Wouldn't we all have evolved the same? Unfortunately our generation reports primarily on theory and prediction.Â 90% of what you read in the newspapers in B.S.

Once again, an article based on theory rather than fact. Evolution negates God's creations. Why do Apes still have fur if we evolved and lost the fur? Wouldn't we all have evolved the same? Unfortunately our generation reports primarily on theory and prediction.Â 90% of what you read in the newspapers in B.S.

Once again, an article based on theory rather than fact. Evolution negates God's creations. Why do Apes still have fur if we evolved and lost the fur? Wouldn't we all have evolved the same? Unfortunately our generation reports primarily on theory and prediction.Â 90% of what you read in the newspapers in B.S.

All the conjectures I've seen here so far are utterly nonsensical, because they ignore the obvious fact, which they cannot even begin to explain,Â that there is a conspicuous difference between hair-loss in men and women. Women, but not men, have lost the ability to grow facial hair!

JUst for the fun of it, let me now propose my own two-cents' worth conjecture. I propose that hair-loss followed the conspicuous reduction ofÂ size-difference (and therefore also strength-difference), between adult men and adult women, compared to the situation in all other higher apes. I have no idea what might be the adaptive value of that conspicuous reduction in size-difference, but it made it muc more difficult to distinguish between a mature woman of child bearibg age, and a mature man; especially from a distance. Women then evolved large protruding mammaries, which shrivel when they become old, but are very conspicuous in women of a child-bearing age, and makes it very easy to recognize such women even from a distance. Becoming hairless then made the protruding mammaries even more conspicuous,Â Â providing women also lost the ability to grow thick long beards that would completely hide the mammaries.

All the conjectures I've seen here so far are utterly nonsensical, because they ignore the obvious fact, which they cannot even begin to explain,Â that there is a conspicuous difference between hair-loss in men and women. Women, but not men, have lost the ability to grow facial hair!

JUst for the fun of it, let me now propose my own two-cents' worth conjecture. I propose that hair-loss followed the conspicuous reduction ofÂ size-difference (and therefore also strength-difference), between adult men and adult women, compared to the situation in all other higher apes. I have no idea what might be the adaptive value of that conspicuous reduction in size-difference, but it made it muc more difficult to distinguish between a mature woman of child bearibg age, and a mature man; especially from a distance. Women then evolved large protruding mammaries, which shrivel when they become old, but are very conspicuous in women of a child-bearing age, and makes it very easy to recognize such women even from a distance. Becoming hairless then made the protruding mammaries even more conspicuous,Â Â providing women also lost the ability to grow thick long beards that would completely hide the mammaries.

All the conjectures I've seen here so far are utterly nonsensical, because they ignore the obvious fact, which they cannot even begin to explain,Â that there is a conspicuous difference between hair-loss in men and women. Women, but not men, have lost the ability to grow facial hair!

JUst for the fun of it, let me now propose my own two-cents' worth conjecture. I propose that hair-loss followed the conspicuous reduction ofÂ size-difference (and therefore also strength-difference), between adult men and adult women, compared to the situation in all other higher apes. I have no idea what might be the adaptive value of that conspicuous reduction in size-difference, but it made it muc more difficult to distinguish between a mature woman of child bearibg age, and a mature man; especially from a distance. Women then evolved large protruding mammaries, which shrivel when they become old, but are very conspicuous in women of a child-bearing age, and makes it very easy to recognize such women even from a distance. Becoming hairless then made the protruding mammaries even more conspicuous,Â Â providing women also lost the ability to grow thick long beards that would completely hide the mammaries.

Also, humans evolved to the point where they are born at a much earlier developmntal stage than newborn in other higher apes, and will need a very long time to reach the stage where they can hold onto their mother's body on their own (even if she were hairy). A human mother must, therefore, hold her baby against the front of her chest. And to enable the baby to suckle, it must be able to find her teats, which it would hardly be able to do, if she grew a thick bushy beard that would cover her breasts; all the more so when humans evolved an erect gait in addition..

Also, humans evolved to the point where they are born at a much earlier developmntal stage than newborn in other higher apes, and will need a very long time to reach the stage where they can hold onto their mother's body on their own (even if she were hairy). A human mother must, therefore, hold her baby against the front of her chest. And to enable the baby to suckle, it must be able to find her teats, which it would hardly be able to do, if she grew a thick bushy beard that would cover her breasts; all the more so when humans evolved an erect gait in addition..

Also, humans evolved to the point where they are born at a much earlier developmntal stage than newborn in other higher apes, and will need a very long time to reach the stage where they can hold onto their mother's body on their own (even if she were hairy). A human mother must, therefore, hold her baby against the front of her chest. And to enable the baby to suckle, it must be able to find her teats, which it would hardly be able to do, if she grew a thick bushy beard that would cover her breasts; all the more so when humans evolved an erect gait in addition..

I'm glad Dirk Meijers has mentioned the aquatic ape theory, which seems to be the most logical explanation. It does require Lamarckian inheritance though, but that is gradually becoming accepted though not publicised.

When I saw the headline I immediately thought "fleas." Â When our ancestors moved indoors they began to spend a lot of time in very close proximity to one another; Â if ectoparasites weren't a threat, our tree-dwelling relatives wouldn't spend so much time grooming one another (and becoming much more socialized).

I'm glad Dirk Meijers has mentioned the aquatic ape theory, which seems to be the most logical explanation. It does require Lamarckian inheritance though, but that is gradually becoming accepted though not publicised.

When I saw the headline I immediately thought "fleas." Â When our ancestors moved indoors they began to spend a lot of time in very close proximity to one another; Â if ectoparasites weren't a threat, our tree-dwelling relatives wouldn't spend so much time grooming one another (and becoming much more socialized).

I'm glad Dirk Meijers has mentioned the aquatic ape theory, which seems to be the most logical explanation. It does require Lamarckian inheritance though, but that is gradually becoming accepted though not publicised.

When I saw the headline I immediately thought "fleas." Â When our ancestors moved indoors they began to spend a lot of time in very close proximity to one another; Â if ectoparasites weren't a threat, our tree-dwelling relatives wouldn't spend so much time grooming one another (and becoming much more socialized).